JP2002527931A - Method and apparatus for communicating auxiliary and location information between a cellular telephone network and a global positioning system - Google Patents

Abstract

SUMMARY The present method and apparatus communicate auxiliary and location information between a cellular telephone network and a mobile station GPS receiver to identify the location of a mobile station. A dedicated channel between the mobile station and the cellular telephone network is allocated by the cellular telephone network and the uplink timing between the mobile station and the cellular telephone network is coordinated. The cellular telephone network requests auxiliary information and requests the GPS receiver to perform a GPS code shift search at a common reference time. Upon receiving the auxiliary information, the cellular telephone network sends the auxiliary information to a GPS receiver, which then performs a GPS code shift search. The GPS receiver includes a plurality of correlators and accumulators, and performs a multi-parallel search for various Doppler frequencies obtained by moving the GPS receiver. The mobile station continuously transmits location information to the cellular telephone network.

Description

DETAILED DESCRIPTION OF THE INVENTION

CROSS-REFERENCE TO RELATED APPLICATIONS This application is filed on Oct. 15, 1997, and is a US patent application serial number entitled “Reduced Global Positioning System Receiver Code Shift Search Time Reduction for Cellular Telephone Systems”. 08 / 950,690 (Document No. 27951-00
170, Inventors: William Camp, Kambitz Zanghi, Rajaram Ramesh), the disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a method and apparatus for reducing the code shift search time of a global positioning system receiver, and more particularly, in a cellular telephone network. The present invention relates to reducing a code shift search time in a global positioning system receiver mounted on an operating cellular mobile station. 2. Description of the Prior Art The provision of the ability to determine the geographical location of a group of cellular telephones operating within a cellular telephone network may be and will likely be required in the future for cellular telephone networks. In order to satisfy this need, it has been proposed to mount a global positioning system (GPS) receiver on the cellular phone to determine the location of the cellular phone. However, GPS receivers are expensive, increase the size of cellular phones, and consume the limited amount of battery power available with cellular phones.

[0002] GPS receivers include, for example, the number of satellites in range, the number of gold codes used by these satellites, the Doppler frequency of the signals transmitted by these satellites, the users located in the center cell from these satellites. And auxiliary information, also known as side information, that refers to information such as the search window size for the Gold code used by each satellite in the coverage area.

[0003] A typical GPS receiver includes at least a signal acquisition circuit, a demodulation and decoding circuit. Most of the complexity comes from this signal acquisition circuit. The signal acquisition circuit
Attempt to search for all Gold codes used in GPS systems with unknown frequency and timing. The purpose is to identify the Gold code, code redundancy and Doppler frequency used by GPS satellites. This is a rather complex and power-consuming process because of the three-dimensional search (sign-time-frequency)
This is because When the GPS receiver acquires the GPS signal, the calendar table data to be read out becomes substantially linear. If auxiliary information is provided to the GPS receiver, such a 3
The complexity of the dimensional search process can be significantly reduced.

However, calculating auxiliary information for a GPS receiver requires that the exact location of the GPS receiver be known. Also, since the position around the actual position of the GPS receiver is used in the calculation of the auxiliary information, fewer position searches have to be performed by the GPS receiver. Fewer searches greatly simplifies the timing process. This search can reduce the need to detect the relative code shift position arrangement in a cycle much shorter than the 1 ms code cycle. When the code shift position is arranged for the first GPS satellite, the GPS receiver recalibrates its own timing and corrects the error of the predicted code shift position for the remaining GPS satellites. A detailed description of the use of auxiliary information by a GPS receiver is referenced in the above-mentioned cross-reference application.

[0005] The code shift search time also changes depending on the moving speed of the GPS satellite. GPS
As the satellite moves, a Doppler frequency shift, which is an amount dependent on the GPS satellite moving speed, occurs.

Therefore, a GPS installed in a mobile station from a base station of a cellular telephone network
It is advantageous to configure a method and apparatus for communicating auxiliary information to a receiver, and
By reducing the time required to determine the position of the GPS receiver, the GPS receiver can provide satellite altitude information such that the GPS receiver can search for the code shift position of the satellite with the highest elevation. Is effective. Further, it is also effective when adapting the movement of the GPS receiver to the code shift search. SUMMARY OF THE INVENTION The present invention comprises a method and apparatus for communicating auxiliary and location information between a cellular telephone network and a mobile station GPS receiver. A dedicated channel between the mobile station and the cellular telephone network is allocated by the cellular telephone network, and the uplink timing between the mobile station and the cellular telephone network is coordinated. The cellular telephone network requests auxiliary information, which includes satellite elevation information among other auxiliary information, and upon receiving the auxiliary information, the cellular telephone network performs a GPS code shift search at a common reference time To send the auxiliary information to the GPS receiver to perform a GPS code shift search using the auxiliary information. The GPS receiver includes a plurality of correlators and accumulators that perform two-dimensional searches of different time shifts and accumulators. The mobile station continuously transmits the time of arrival information to the cellular telephone network. DETAILED DESCRIPTION OF THE EMBODIMENTS Referring first to FIG. 1, an overview of elevation angles of a plurality of global positioning system satellites with respect to a global positioning system receiver is shown. A plurality of Global Positioning System (GPS) satellites 100A within the coverage of the GPS receiver 110 of the mobile station 111
ＮN have elevation angles A〜N. Typically, the GPS receiver 11 at any time
Within the reception range of 0, there are 5 to 8 GPS satellites 100A to 100N.

[0007] Still referring to FIG. 2, a block diagram of auxiliary information provided to a global positioning system receiver is shown. The auxiliary information 140 includes a list 150 of a plurality of GPS satellites 100A to 100N within the reception range of the GPS receiver and a plurality of GPS satellites 100A to 100N.
A respective Doppler correction 170, a reference code shift position 180 referring to a predicted code shift position for the user at a reference position within the cell (eg, the center of the cell), a code shift for each of the plurality of GPS satellites 100A-N based on Coordinated Universal Time. Search uncertainty 185 and elevation angle 190 for each GPS satellite on list 150
Contains. Optionally, the list of elevations 190 is omitted and the satellite 100A
〜N are arranged on the list 150 in an order according to the elevation angles A よ う な N such that the GPS receiver 110 can identify the satellite having the maximum elevation angle A〜N.

Referring to FIG. 3, a flow diagram of a method for performing call setup of the present invention is shown. If the request from the mobile station is an emergency call (step 300), the cellular telephone network may use the time advance command to provide uplink timing with a time advance command such that the continuous burst transmitted by the mobile station is synchronized with the serving antenna interface of the serving base station. (Step 310) and allocate a dedicated channel between the mobile station and the cellular telephone network (step 305). For example, in a Global System for Mobile Station Communication (GSM) system, a mobile station requests a channel on a random access channel (RACH) and the cellular telephone network transmits an access grant channel (AGCH) burst to allocate a dedicated channel. . To determine the mobile station's reference time, the cellular telephone network estimates the round trip propagation delay between the mobile station and the serving base station by measuring the timing of the RACH burst transmitted by the mobile station. The serving base station requests auxiliary information (step 320) and sends a request to the mobile station's GPS receiver to perform a GPS code shift search at the common reference time (step 330). At the time of the common reference, it is specified as the uplink absolute frame number (AFN). The serving base station receives the auxiliary information (step 340) and transmits the auxiliary information to the GPS receiver of the mobile station (step 350). The auxiliary information is transmitted to the mobile station via a GSM cellular telephone network standalone dedicated control channel (SDCCH), a digital advanced mobile telephone service (DAMPS) digital control channel, or a short message service (SMS) message.

[0009] The GPS receiver of the mobile station performs a GPS code shift search using the specific uplink absolute frame number using the auxiliary information (step S360). The GPS receiver first searches for the satellite with the maximum elevation using the satellite elevation information. Correlations at different code phases between the received GPS signal and the Gold code generated at the GPS receiver are calculated. It is understood that a GPS signal is a spread spectrum signal that uses direct sequence modulation, where each code is spread by a Gold code. Due to the Doppler effect, the chip period of the received GPS signal is different from the chip period of the Gold code generated by the GPS receiver. As a result, a chip slip occurs in the GPS receiver. The Doppler frequency of the received GPS signal is GP
Provided to the S receiver, the GPS receiver adjusts its chip slip if it needs to perform an accurate code shift search. The code chip redundancy in uplink absolute frames is used as a base station line reference for chip redundancy used to adjust chip slip. When the mobile station GPS receiver completes the code shift search for each of the GPS satellites listed in the auxiliary information,
The measurement time is transmitted to the base station (step 370), and the cellular telephone network converts the measurement time to a measurement range (step 380).

Referring to FIG. 4, a functional block diagram of a plurality of correlators and accumulators for reducing the code shift search time of a global positioning receiver is shown. To perform a code shift search, GPS receiver 110 uses auxiliary information 140 to
A Doppler frequency f (A to N) and a reference code delay t (A to N) for each of the satellites 100A to 100N are generated. Gold code generator 400 uses auxiliary information 140 to generate a gold code for each of GPS satellites 100A-N. G
The PS receiver 110 inputs the Gold code to the delay line sequence 410 and generates a Gold code having a different delay.

The plurality of correlators 420 calculate a correlation between a received GPS signal and a plurality of Gold codes having different delays. The plurality of correlators 420 provide a plurality of correlation values.

[0012]

(Equation 1) Where m indicates that the correlation is performed at intervals of 1 / m millisecond, which is the period of the Gold code, and L indicates the number of added delays. However, to obtain a relative code shift search in low signal-to-noise conditions, correlation over a long time period of 1 ms or more is required. Various problems arise when calculating correlations over long time periods. First, the reference Doppler frequency f (AN) obtained from the cellular telephone network, which is a frequency predicted by a user located at a reference position (for example, the center of the cell) in the cell, is 10 times lower than the actual Doppler frequency.
The coherence loss occurs due to the fact that it can go above Hertz. The frequency difference causes a carrier phase fluctuation of 10 cycles or more every second. The second problem is GP
Include coherent timing, which is the ability of the S receiver 110 to move fast. For example, GPS traveling at 60 miles per hour
Receiver 110 has a coherence time that is one-twelfth of the coherence time of GPS receiver 110 traveling at three miles per hour. And the GPS satellites 100A to N
And the code chip slip due to the difference between the frequency criteria at the GPS receiver 110 is
The longer the correlation time period, the more pronounced.

In order to address these problems and reduce the code shift search time, a plurality of correlation values at 1 / n millimeter line intervals are used.

[0014]

(Equation 2) Is a vector generated by the vector generator 430.

[0015]

(Equation 3) And output to a plurality of accumulators 440 along with a reference Doppler frequency f (AN) and a reference code delay t (AN), where different combinations of millisecond correlation vectors

[0016]

(Equation 4) Combine with For example, the first accumulator performs coherent combining in 2 milliseconds,
That is, the l-th vector element is given by the following equation.

[0017]

(Equation 5) Here, the inner sum is coherent combining, and the outer sum is non-coherent combining. Similarly, the last accumulator P performs coherent combining according to the following equation:

[0018]

(Equation 6) By performing multiple types of combinations of coherent combining, each accumulator 440 is designed to be optimized for the GPS receiver 110 moving at different speeds. That is, the first accumulator operates optimally for the fast moving GPS receiver 110, while the accumulator P operates optimally for the stationary GPS receiver 110.

Finally, the maximum cumulative value according to the cumulative value of the two adjacent values of the same vector is
50, where the quadratic interpolation algorithm is used to generate the peak value. The peak value corresponds to the location information, which is returned to the cellular telephone network for location determination.

Referring to FIG. 5, there is shown a flow diagram of a method for reducing the code shift search time of the global positioning receiver of the block diagram of FIG. Utilizing delay line 410, various delay gold codes are generated (step 510). The plurality of correlators 420 calculate a correlation value from the Gold code and the received GPS signal (Step 520).
The parallel vector generator 430 serializes the calculated correlation value (step 53).
0), the plurality of accumulators 440 perform coherence combining of the serialized correlation values (step 540), and generate respective accumulated values (step 550). 2
The secondary interpolator 450 performs quadratic interpolation on the output of the accumulator with the largest accumulated value and the outputs of the two correlators 420 adjacent to the accumulator (step 560).

Embodiments of the method and apparatus of the present invention are illustrated and described in the above detailed description, together with the drawings, but the invention is not limited to the disclosed embodiments, but is defined by the claims and It will be understood that numerous rearrangements, modifications and alternatives are possible without departing from the spirit of the invention described.

[Brief description of the drawings]

FIG. 1 is an overview of elevation angles for a plurality of global positioning systems for a global positioning system receiver.

FIG. 2 is a block diagram of auxiliary information transmitted from a base station to a mobile station.

FIG. 3 is a flow diagram of a method for performing a call setup according to the present invention.

FIG. 4 is a functional block diagram of a plurality of correlators and accumulators for reducing a code shift search time of a global positioning receiver.

5 is a flowchart of a method for reducing a code shift search time of the global positioning receiver in the block diagram of FIG. 4;

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] December 15, 2000 (2000.15)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID , IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW (71) Applicant 7001 Development Drive, P.E. O. Box 13969, Re search Triangle Park, NC 27709 U.S.A. S. A. (72) Inventor Cennakesh, Sundeep 27513 North Carolina, USA Carry, Glen Abbey Drive 311 F-term (reference) 5J062 AA08 BB05 CC07 DD12 EE03 5K067 AA15 BB02 CC04 CC10 DD20 DD25 EE02 EE10 EE12 EE71 JJ52 JJ56

Claims (14)

[Claims] 1. A method of communicating auxiliary information and location information between a cellular telephone network and a GPS receiver of a mobile station, comprising: allocating a dedicated channel between the mobile station and the cellular telephone network; Adjusting the uplink timing between the mobile telephone and the cellular telephone network; requesting auxiliary information; requesting the GPS receiver to perform a GPS code shift search at a common reference time; Transmitting the auxiliary information to a GPS receiver of the following, performing the GPS code shift search, and transmitting the location information to the cellular telephone network. 2. The method according to claim 1, wherein the transmitted location information is a physical location of the GPS receiver. 3. The method according to claim 1, wherein the transmitted location information is timing information indicating a location of the GPS receiver. 4. The method of claim 1, further comprising: identifying an incoming call to the cellular telephone network as an emergency call. 5. The method of claim 1, wherein allocating the dedicated channel comprises transmitting a signal burst on another channel in response to a request from the mobile station. 6. The method of claim 1, wherein allocating the dedicated channel comprises transmitting an access grant channel burst on a random access channel in response to a request from the mobile station. 7. The step of requesting the GPS receiver to perform a GPS code shift search at the common reference time requests the GPS receiver to perform the GPS code shift search at a common reference time. The method of claim 1, comprising the steps of: 8. Transmitting the auxiliary information to the GPS receiver comprises transmitting the auxiliary information on a stand-alone dedicated control channel of a global system for a mobile communication cellular telephone network. Item 1. The method according to Item 1. 9. The method of claim 1, wherein transmitting the auxiliary information to the GPS receiver comprises transmitting the auxiliary information over a digital control channel of a digital advanced mobile telephone service cellular telephone network. The method described in. 10. The method of claim 1, wherein transmitting the auxiliary information to the GPS receiver comprises transmitting the auxiliary information in a short message service message. 11. The method according to claim 1, wherein the auxiliary information includes a satellite elevation angle of each GPS satellite included in the auxiliary information. 12. The method according to claim 1, wherein the GPS satellites included in the auxiliary information are arranged in descending order according to their elevation angles. 13. A delay line train for generating gold codes with different delays, a plurality of correlators for calculating correlation values between the gold codes with different delays and received GPS signals, and vector generation for vectorizing the correlation values A plurality of accumulators, designed to fit GPS receivers moving at different speeds, for performing coherent combining of the serialized correlation values and producing an accumulated value; and A second interpolator for performing quadratic interpolation on the output of the accumulator and the outputs of two correlators adjacent to the accumulator. 14. Generating a Gold code with various delays, calculating a correlation value between the Gold code and a received GPS signal, serializing the calculated correlation value, and coherence of the serialized correlation value. Performing a synthesis, generating a cumulative value, and performing a quadratic interpolation of the selected cumulative value.